M - Help Jimmy POJ - 1661 ——dp

dp[i][0]:表示从第i个木板左端点跳跃的当前最优解
dp[i][1]:表示从第i个木板右端点跳跃的当前最优解

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int inf = 0x3f3f3f3f;

struct Node{
int x1, x2;
int h;
bool operator < (const Node &b) const {
return h < b.h;
}
}node[1014];

int H, dp[1014][2];
/*
dp[i][0]:表示从第i个木板左端点跳跃的当前最优解
dp[i][1]:表示从第i个木板右端点跳跃的当前最优解
*/

void left_time(int z, int n);
void right_time(int z, int n);
void ans_time(int n);

int main(){
int T, i, n, x, y;
scanf("%d", &T);
while(T--){
scanf("%d %d %d %d", &n, &x, &y, &H);
node[n+1].x1 = node[n+1].x2 = x, node[n+1].h = y;
node[0].x1 = -20000, node[0].x2 = 20000, node[0].h = 0;
for(i = 1; i <= n; i++)
scanf("%d %d %d", &node[i].x1, &node[i].x2, &node[i].h);
sort(node, node+n+2);
ans_time(n);
}
return 0;
}
void left_time(int z, int n){/*第z个左端点跳跃*/
for(int i = z-1; i > 0; i--){/*注意i的范围:[1, z-1]*/
int dh = node[z].h - node[i].h;
if(dh <= H && node[i].x1 <= node[z].x1 && node[i].x2 >= node[z].x1){/*判断是否满足直接落在木板上的条件*/
int u = node[z].x1 - node[i].x1;
int v = node[i].x2 - node[z].x1;
dp[z][0] = dh + min(dp[i][0]+u, dp[i][1]+v);
return;/*已经直接落在木板上*/
}
}
if(node[z].h <= H)/*判断是否可直接跳到地面上*/
dp[z][0] = node[z].h;
else
dp[z][0] = inf;
}
void right_time(int z, int n){/*第z个右端点跳跃*/
for(int i = z-1; i > 0; i--){/*注意i的范围:[1, z-1]*/
int dh = node[z].h - node[i].h;
if(dh <= H && node[i].x1 <= node[z].x2 && node[i].x2 >= node[z].x2){/*判断是否满足直接落在木板上的条件*/
int u = node[z].x2 - node[i].x1;
int v = node[i].x2 - node[z].x2;
dp[z][1] = dh + min(dp[i][0]+u, dp[i][1]+v);
return;/*已经直接落在木板上*/
}
}
if(node[z].h <= H)/*判断是否可直接跳到地面上*/
dp[z][1] = node[z].h;
else
dp[z][1] = inf;
}
void ans_time(int n){
memset(dp, 0, sizeof(dp));
for(int i = 1; i <= n+1; i++){
left_time(i, n);/*试探左端点跳跃的最短时间*/
right_time(i, n);/*试探右端点跳跃的最短时间*/
}
printf("%d\n", min(dp[n+1][0], dp[n+1][1]));
}